Flow control valve

Abstract

A flow control valve includes: an inlet casing concentric to a spindle; an outlet casing coupled with the inlet casing, an inlet portion of the outlet casing having a countersunk edge part; a head having two notches in the surface of a cylindrical portion, the head being put into the outlet casing; and a disk shaped as a truncated cone which is continuously provided to the head, the disk coming into contact with the countersunk edge part.

What is claimed is: 
     
       1. A flow control valve comprising: a valve spindle;   a metal inlet casing concentric with said valve spindle;   a metal outlet casing coupled to said inlet casing, an inlet portion of said outlet casing having a countersunk edge portion; and   a valve head coupled to an end of said valve spindle, said valve head comprising: a cylindrical portion having a surface cut by a pair of notches disposed opposite one another across a longitudinal axis of said valve head and a pair of generally flat cut parts disposed opposite one another and between said notches, one of said notches being longer than the other of said notches in said longitudinal direction of said valve head, a surface of said cut parts extending obliquely to said longitudinal axis of said valve head, and   a disk portion formed upstream of and continuous with said cylindrical portion, said disk portion being shaped as a truncated cone, at least a surface portion of said disk portion being made of a resin material, said disk portion being sealed against said countersunk edge portion of said outlet casing when said valve is closed.     
     
     
       2. The flow control valve of claim 1, further comprising means for driving said valve spindle so as to position said valve head at a desired position between a fully opened position and a fully closed position. 
     
     
       3. The flow control valve of claim 1, wherein said inlet casing and said outlet casing are made of stainless steel. 
     
     
       4. The flow control valve of claim 1, wherein said resin material of said disk portion is tetrafluoroethylene. 
     
     
       5. The flow control valve of claim 1, wherein said disk portion is formed entirely of said resin material. 
     
     
       6. The flow control valve of claim 1, wherein only said surface portion of said disk portion is formed of said resin material, while remaining portion of said disk portion and said cylindrical portion are made of metal.